In some application scenarios, determining a position of an object of interest of a user relative to the user may be used to: determine the object of interest of the user, automatic focus for photography, locate the user according to the object whose coordinates are known, determine whether attention of the user is distracted, and perform other operations. When a user gazes an object in motion, a phenomenon of smooth pursuit eye movement generally occurs. The smooth pursuit eye movement is an eye movement behavior of continuous visual pursuit of a motion object of interest of the user in an environment.